Note: Descriptions are shown in the official language in which they were submitted.
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RUBBER CYLINDER SLEEVE FOR OFFSET WEB-FED
ROTARY PRINTING MACHINES
Field of the Invention
The present invention is directed to a cylinder
sleeve and, more particularly, to a rubber cylinder sleeve
for an offset web-fed rotary printing machine.
Description of the Related Art
Rubber cylinder sleeves are disclosed in U.S. Patent
Nos. 5,429,048, 5,323,702, 5,440,981 and 5,304,267. The
sleeves disclosed in these references include intermediate
and lower layers which must disadvantageously be at least
partially continuous, or endless generally increasing
production costs.
Another type of rubber cylinder sleeve is disclosed
in U.S. Patent No. 5,351,615. This cylinder sleeve is
formed by first securing a rubber blanket to a carrier
plate, such as, for example, by gluing, with both the
rubber blanket and carrier plate being substantially
planar prior to being formed into a cylinder. This
combination is then formed into a cylinder sleeve by
bringing the ends of the combined rubber blanket and
carrier plate into confronting relation with each other
and by joining the respective confronting ends together,
preferably by welding or gluing. Although this
arrangement produces a virtually gap-free joint, a
connection seam remains on the surface of the finished
rubber sleeve at the joint. This disadvantageously
presents an imperfect outer surface on the cylinder sleeve
and adversely impacts the print quality of sleeves so
constructed.
Summary of the Invention
It is accordingly an object of the present invention
to produce a rubber cylinder sleeve particularly suited
for an offset web-fed rotary printing machine that
overcomes the above-mentioned shortcomings of the prior
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art, that may be economically produced, and that is
capable of at least the same printing quality and printing
behavior as prior art sleeves.
In general, a rubber cylinder sleeve comprises a
carrier sleeve, preferably made of metal or reinforced
glass-fiber. Elastic properties inherent to the preferred
metal and glass-fiber materials permit the carrier sleeve
to radially expand when a compressed gas, such as air, for
example, is outwardly directed at an inner surface of the
carrier sleeve. These inherent elastic properties also
permit the carrier sleeve to elastically contract and
return to its non-expanded condition upon removal of the
compressed gas, thereby securing the cylinder sleeve on
the transfer cylinder. The inherent elasticity of the
carrier sleeve facilitates sliding the cylinder sleeve
onto and off of a transfer cylinder or rubber blanket
cylinder (as this device is referred to for printing
machines that employ the indirect method of printing).
Openings may be provided in the transfer cylinder to
direct the compressed air toward the inner surface of the
carrier sleeve thereby facilitating expansion thereof.
Once the cylinder sleeve is in the desired position and
the source of compressed air is removed, the carrier
sleeve will contract, thereby firmly seating the cylinder
sleeve on the transfer cylinder. Accordingly, a cylinder
sleeve configured according to the present invention may
advantageously be slid onto and off of the transfer
cylinder through an opening in a sidewall of the printing
machine.
At least one additional layer which is preferably
compressible, is applied - directly or indirectly - about
the outer perimeter of the carrier sleeve. This
compressible layer contains air inclusions such as, for
example, air-bubbles embedded within the material of the
compressible layer. At least one cover layer, which may
be made from elastomeric material, for example, is
provided over the compressible layer. This cover layer
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permits the images to be printed to be transferred from a
form cylinder or printing form, e.g. an offset printing
plate or a sleeve-type offset printing form, to printing
stock. The cover layer may also contain air inclusions,
in which case the cover layer is less compressible than
the above-described compressible layer.
Another layer which is not expandable, a . g. which is
made of a hard elastomeric material or that has short
fibers or threads embedded within a hard elastomeric
material, is preferably provided between the compressible
layer and the cover layer. Alternatively, a nonexpandable
layer or nonexpandable particles, such as threads or
pieces of threads, can also be introduced directly into
the compressible layer discussed above to render a portion
of the compressible layer nonexpandable.
According to one broad aspect of the present
invention, there is provided a cylinder sleeve for an
offset printing machine. The cylinder sleeve comprises: a
carrier sleeve having a joint location; a compressible
layer arranged on an outer side of the carrier sleeve and
having a joint location; and a jointless cover layer
arranged on an outer side of the compressible layer.
According to another broad aspect of the present
invention, there is provided a cylinder sleeve for an
offset printing machine. The cylinder sleeve comprises: a
carrier sleeve; and an outer layer arranged on an outer
side of the carrier sleeve, containing air inclusions and
partly comprised of non-expandable material.
According to still another broad aspect of the
present invention, there is provided a cylinder sleeve for
an offset printing machine having a transfer cylinder, the
transfer cylinder having an outer conical jacket surface
and including radial bore holes located in an end region
of the jacket surface, the radial bore holes providing a
path for compressed air. The cylinder sleeve comprises: a
carrier sleeve comprised of expandable material having a
substantially conical inner jacket surface; and an outer
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layer arranged on an outer side of the carrier sleeve
containing air inclusions and partly comprised of non-
expandable material, the compressed air being directed
from the radial bore holes generally toward the inner
jacket surface of the carrier sleeve to radially expand
the carrier sleeve.
Other objects and features of the present invention
will become apparent from the following detailed
description considered in conjunction with the
accompanying drawings. It is to be understood, however,
that the drawings are designed solely for purposes of
illustration and not as a definition of the limits of the
invention, for which reference should be made to the
appended claims.
Brief Description of the Drawings
In the drawings, wherein like reference characters
denote similar elements throughout the several views:
Fig. 1 is a partial cross-sectional view of a
cylinder sleeve configured according to the present
invention and disposed on a transfer cylinder;
Fig. 1a is a partial cross-sectional view of a
carrier sleeve having an offset rubber blanket and
configured according to the present invention;
Fig. 2 is a cross-sectional view of a carrier sleeve
having a generally conical internal cross-section
configured according to the present invention and
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partially disposed on a transfer cylinder, the transfer
cylinder being shown in partial cross-section;
Fig. 3 is a partial sectional view of the carrier
sleeve of Fig. 2;
Fig . 4 is a partial sectional view of an alternative
embodiment of a carrier sleeve having a metal inner
carrier and a plastic cover layer and configured according
to the present invention; and
Fig. 5 is a partial sectional view of an alternative
embodiment of a carrier sleeve having a glass-fiber
reinforced inner carrier and an epoxy resin outer coating
and configured according to the present invention.
Detailed Description of the Preferred Embodiments
The present invention provides a rubber cylinder
sleeve that may be easily slid onto and off of the
transfer cylinder of a web-fed rotary printing machine
due, in part, to the elastic properties inherent in the
preferred materials used to construct the invention
cylinder sleeve. The outer-most layer of the inventive
cylinder sleeve may be slightly compressible, but only to
a limited degree so as not to distort or otherwise impact
the printing quality of the inventive device. Various
compressible and nonexpandable layers may be provided, in
generally layered relation, about a carrier sleeve, to
form the inventive cylinder sleeve. By varying the number
and composition of the layers, and by varying the
materials used to construct the several layers, numerous
embodiments of the present invention are possible.
Referring now to the drawings in detail, Fig. 1
depicts a blanket cylinder sleeve 2 according to the
present invention. The cylinder sleeve 2 is removably
mountable on a transfer cylinder 16 (also referred to as a
blanket cylinder) of a web-fed rotary printing machine
(not shown). The transfer cylinder 16 includes a
plurality of openings or nozzles 26 circumferentially
disposed about its outer surface 52 through which a
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compressed gas such as, for example, air, may pass. The
blanket cylinder sleeve 2 or printing blanket comprises a
carrier sleeve 18 which is preferably expandable by the
compressed air when the cylinder sleeve 2 is slid onto and
off the transfer cylinder 16. A compressible layer 4 may
be secured about the carrier sleeve 18 by glue,
vulcanization or other known securing methods or means.
The compressible layer 4 may contain integrally formed air
inclusions 10 in the form of air bubbles. Alternatively,
other compressible gases or liquids may be provided in the
inclusions 10 of layer 4. The air inclusions 10 and
general compressibility of layer 4 permit the carrier
sleeve 18 to freely expand tencouraged by the compressed
air from nozzles 26) and contract as the compressed air is
direct toward and removed from the inner surface 3 8 ( Fig .
2) of the carrier sleeve 18.
A nonexpandable layer 20, preferably made of a hard
elastomer layer having short fibers interspersed
therethrough, may optionally be disposed about the
compressible layer 4. The non-expandable layer 20 limits
the expansive displacement of the outer surface 32 of the
carrier sleeve 18 in response to the compressed air, while
the compressible layer 4 permits the carrier sleeve 18 to
freely expand and contract. A cover layer 6, that may be
made from an elastic material and that can be used as the
print surface for offset printing, may be
circumferentially displaced about the nonexpandable layer
20. If the nonexpandable layer 20 is not provided, the
cover layer 6 may be disposed directly about the
compressible layer 4. The cover layer 6 may optionally
contain inclusions 10 having a compressible liquid or gas
distributed therein to facilitate compression and
expansion of the cover layer 6. The cover layer 6 is
thus, at least partly compressible -- yielding
corresponding advantageous improvements over the prior art
such as, for example, improved printing results, printing
behavior, and web guidance.
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With continued reference to Fig. 1, the carrier
sleeve 18 is preferably made from steel and advantageously
formed from a generally planar plate whose ends are welded
together resulting in a joint location 22 such as, for
example, a weld seam. Similarly, the compressible layer 4
is formed from a flexible sheet of compressible material
which is then wrapped around the carrier sleeve 18 to form
a continuous compressible layer 4 disposed about the
carrier sleeve 18. To accomplish this, oppositely located
free ends (not shown) of the compressible sheet material
are spliced together or otherwise joined using known
joinery means to form a joint location 8. If a
nonexpandable layer 20 is provided about the compressible
layer 4, a joint location 24 may likewise be formed
thereon. As used herein, the terms joint, joint location
and seam may refer to, by way of non-limiting example, the
location at which two edges or ends of a generally planar
component are joined as the component is formed into a
generally cylindrical or conical member.
In contrast to the above-discussed elements, the
cover layer 6 is configured as a longitudinally continuous
tube or cylinder, having no joints or seams.
When arranging the individual layers of the
inventive cylinder sleeve 2, the joint locations 22, 8, 24
of the carrier sleeve 18, compressible layer 4, and non
expandable layer 20, respectively, need not lie on top of
one another as shown in Fig. 1, but instead, may be
circumferentially spaced apart in any manner and without
regard to the spacial relationship between the various
joint locations 22, 8, 24.
In an alternative embodiment depicted in Fig. la, the
inventive cylinder sleeve 2 may comprise a steel, aluminum
or carbon-fiber plastic carrier sleeve 18 having a joint
location 22 produced by welding the ends or edges of the
carrier sleeve 18 sheet material together to form a
cylinder. A conventional offset printing blanket 56
having an integral compressible layer, a joint location 8,
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and an outermost surface 60 may be applied
circumferentially about the carrier sleeve 18, i.e. in
place of the above-described compressible layer 4. The
printing blanket is applied to the carrier sleeve 18 by
gluing, vulcanization, or other similar affixation means
or methods. The outermost surface 60 of the conventional
printing blanket 56 is then removed, e.g. by grinding, and
a continuous, seamless, cover layer 58 is applied (i.e.
vulcanized) in its place. This method of production and
the resultant cylinder sleeve 2 are substantially cheaper
and have a number of advantages over known sleeves. For
example, when a nonexpandable layer 20 is arranged on top
(as viewed in Fig. la) of the blanket 56, the respective
joint locations 24, 8 lie on top of each other, since they
represent the ends of the conventional blanket 56 which
was glued onto the carrier sleeve 18. However, the joint
locations 24, 8 may - but need not necessarily - be
arranged directly over the joint location 22 in an
advantageous manner.
The inventive cylinder sleeve 2 offers a multitude of
possible uses which are not limited to offset web-fed
rotary printing machines. For example, the cylinder
sleeve 2 may also be used in other indirect printing
methods such as indirect gravure printing or
alternatively, it may can be used as a roller.
A particular advantage of the inventive cylinder
sleeve 2 is that a circumferential register, that is, the
arrangement of the sleeve on the cylinder in a
predetermined circumferential position on the transfer
cylinder 16, is no longer required. However, the known
essential advantages typical of finite transfer carriers
(rubber blankets or rubber sleeves) can nevertheless be
r
achieved in production.
In a preferred embodiment, only the cover layer 6
(i.e. the layer receiving the printing image) is elastic,
and preferably, only the lower region or portion of the
cover layer 6 is constructed with air inclusions 10 or
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possibly air channels which are open at the bottom, i.e.
facing the carrier sleeve 18. Such a layer 6 may include
nonexpandable material, such as threads or thread pieces,
and the layer 6 may be arranged directly on the carrier
sleeve 18.
It is also possible to produce the carrier sleeve 18
from fiber-reinforced hard rubber - with or without a seam
- which is expandable by means of compressed air. A
compressible layer 4 can be placed over the rubber carrier
sleeve 18 followed by a semi-compressible layer which may
be fiber-reinforced, followed by a cover layer 6 -- this
configuration being highly advantageous.
Referring next to Figs. 2-5, a carrier sleeve 18
having a substantially conical inner jacket surface 38
(when viewed in cross-section) will now be described in
greater detail. For the sake of simplicity, the reference
numbers of the previous embodiment shown in Fig. 1 are
used in Figs. 2-5 for similar elements, where appropriate.
Fig. 2 depicts a carrier sleeve 18 partially disposed
on a generally conical transfer cylinder 16 having an
outer or jacket surface 52. The carrier sleeve 18
includes an inner jacket surface 38 shaped complementarily
with the transfer cylinder 16, i.e. substantially conical.
Arranged roughly in the center of the transfer cylinder 16
is a radial bore or channel 50 connected to radial bore
holes 48 located at least near an end region of the jacket
surface 52. The channel 50 and bore holes 48 guide
compressed air from a compressed air source (not shown)
against the inner jacket surface 38 of the carrier sleeve
18 to encourage the carrier sleeve 18 to expand as the
cylinder sleeve 2 is slid onto and off of the transfer
cylinder 16.
As a result of the complementary conical shapes of
the transfer cylinder 16 and carrier sleeve 18, there
exists a gap or clearance between these parts as the
carrier sleeve 18 is initially slid onto the transfer
cylinder 16. Consequently, bevels or other similar
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guidance or alignment devices are not required to assist
in placing the carrier sleeve 18 (and cylinder sleeve 2)
onto the transfer cylinder 16. The compressed air is also
advantageously distributed in this gap as the carrier
sleeve 18 is slid onto the transfer cylinder 16.
Referring next to Fig. 3, the carrier sleeve 18 of
Fig. 2 is partially shown in enlarged longitudinal cross-
section. In this embodiment, the carrier sleeve 18 is
formed of a metal, preferably nickel, having a
substantially cylindrical outer shape as defined by outer
surface 32. Due to the generally cylindrical outer shape
and generally conical inner shape of the carrier sleeve 18
(as defined by the inner jacket surface 38), the cross-
sectional wall thickness of the carrier sleeve 18
increases in the direction of arrow A of Figs. 2 and 3,
i.e. toward the end of the carrier sleeve 18 having a
smaller inner diameter. The carrier sleeve 18 depicted in
Fig. 3 may be produced by electroplating and subsequent
polishing of the outer surface 32.
Referring next to the embodiment depicted in Fig. 4,
the carrier sleeve 18 is formed of a metal inner carrier
30, preferably made of nickel and having an inner jacket
surface 34 and an outer jacket surface 36, both of which
define a generally conical shape. In this embodiment, the
inner carrier 30 may be formed initially from a metal
sheet having longitudinally opposite ends or edges which
are bent toward one another as the sheet is formed into a
generally conical shape. Once bent thusly, the edges lie
confrontingly opposite one another and may be joined
together by, for example, laser-welding, to generally form
a joint location 22 (Fig. 1). A stationary plastic cover
layer 12 having an outer surface 40 that defines a
generally cylindrical shape and an inner surface 54 that
defines a generally conical shape, is arranged on the
inner carrier 30. In a preferred embodiment, the plastic
cover layer 12 is formed of hard rubber and advantageously
vulcanized or glued onto the inner carrier 30 and then
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polished. The plastic cover layer 12 may be constructed
with or without a joint.
An alternative embodiment of the carrier sleeve 18 is
shown in part in Fig. 5. Here, the carrier sleeve 18 is
formed of a multi-layered glass-fiber reinforced plastic
(GFP) 28 having substantially conically shaped inner and
outer surfaces 44 and 46, respectively. An epoxy resin
coat 14 having a substantially cylindrically shaped outer
surface 42 is disposed circumferentially about the multi-
layered glass-fiber plastic 28, which is preferably a
rolled glass-fiber coat.
The various carrier sleeve 18 embodiments described
above and shown in Figs. 2-5 may include one of the
coatings described above, e.g. stationary plastic or epoxy
resin.
Thus, while there have shown and described and
pointed out fundamental novel features of the invention as
applied to preferred embodiments thereof, it will be
understood that various omissions and substitutions and
changes in the form and details of the devices
illustrated, and in their operation, may be made by those
skilled in the art without departing from the spirit of
the invention. For example, it is expressly intended that
all combinations of those elements and/or method steps
which perform substantially the same function in
substantially the same way to achieve the same results are
within the scope of the invention. It is the intention,
therefore, to be limited only as indicated by the scope of
the claims appended hereto.
